PassMark is a synthetic benchmark, not a real world benchmark. That graph shows a number... but what exactly does that
number mean? What CPU was in the system that recorded that PassMark score? What RAM? Liquid or air cooled? Here is
a synthetic benchmark that shows the 570 GTX is better than the 480 GTX.

Read this, it's is an older article that might shine some light on the subject of benchmarks.

I'm not, by any means, saying the 480 GTX is a bad card, because it was top notch for its time. However, the card was
quickly replaced 6 months after its release because it had a handful of issues which were resolved in the 5xx generation.
The 480's are going for super cheap because retailers are just getting rid of their old stock. I paid more for my 460 GTX
a few weeks ago and the 480 GTX is a more powerful card.

The moral of the story is:

Don't use synthetic benchmarks to purchase computer hardware unless you're specifically dealing with those benchmarks
for a reason.